This is a revision of the competitive continuation application for the HIV Center for Clinical and Behavioral Studies. The Center is dedicated to multidisciplinary research on the prevention and transmission of HIV and on the improvement of HIV-infected people's lives with an emphasis on sexual risk behavior and the critical role of gender in effective interventions. We are proposing seven Cores: (1) the Administrative Core, to provide the leadership to both stimulate and manage innovative research, ensuring the highest scientific standards, ethical integrity, and efficient fiscal operations; (2) the Interdisciplinary Research Methods Core, to provide consultation and oversight for HIV-related sexuality research including, theoretical conceptualization, qualitative and quantitative measurement, and intervention development; and a forum for analysis of theoretical and methodological issues in HIV prevention science; (3) the Statistics, Epidemiology, and Data Management Core, to provide a centralized resource for statistical planning and analysis, for expert consultation on study design and execution, and for data management; (4) the Community Collaboration Core, to promote community-academic partnerships for the generation, adaptation, and dissemination of HIV behavioral research and to develop theoretical models and methodologies necessary to understand the collaborative process and optimize outcomes of partnerships; (5) the Research Capacity Development Core, to attract and ensure the growth and development of junior investigators -particularly those from ethnic/racial minority backgrounds -and foster new HIV-related sexuality and gender pilot research; (6) the International Core, to coordinate the development of international research initiatives by HIV Center investigators and their in-country partners and develop comparative analyses of key theoretical and topical issues relevant to the global response to HIV and AIDS; and (7) the Ethics, Policy, and Human Rights Core, to provide mechanisms for advancing the consideration of ethics and policy implications in HIV Center research and stimulate research on ethics, policy, and human rights. This application represents a mandated transition from a P50 to a P30 mechanism and revises the infrastructure of the Center so as to provide a rich resource to a larger number of investigators, while enhancing the Center's ability to attract and train new investigators and to make innovative scientific, programmatic, and policy contributions that respond to the evolving HIV/AIDS epidemic on a national and international level.